Development of a Prosthetic Eye

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ENGINEERING TECHNICAL COMMUNICATIONS

 

A Vision without Sight

TABLE OF CONTENTS

1 Executive summary……………………………………………………………………………………………..04

2 Introduction…………………………………………………………………………………………………………06

3 Background and Literature review………………………………………………………………………….07

 3.1 Background review………………………………………………………………………………07

 3.2 Literature review…………………………………………………………………………………….08

4 Requirements and criteria………………………………………………………………………………………09

5 Proposed Design Solution……………………………………………………………………………………..10

 5.1 Working of a normal eye………………………………………………………………………..10

 5.2 Retinal degenerative disease – Aged Macular degeneration………………………..11

  5.3 Retinitis pigmentosa ………………………………………………………..11

 5.4 Design of prosthetic eye……………………………………………………… 11

 5.5 Components of prosthetic eye……..………………………………………… 11

 5.6 Working of prosthetic eye …………………………………………………… 11

 5.7 Results and comparison of firing patterns…………………………………… 12

 5.8 Strength and limitations…………… ………………………………………… 12

6 Cost…………………………………………………………………………………………………………………15

7 Timeline………………………………………………………………………………………………………………16

8 Conclusions………………………………………………………………………………………………………….17

9 References ………………………………………………………………………………..18

LIST OF FIGURES

Figure I: Late 20th century custom made Poly methyl methacrylate (PMMA) eye…….07

Figure II: Working of an eye…………………………………………………………….10

Figure III: Retinal degenerative diseases………………………………………………..10

Figure IV: Schematic of modern prosthetic eye…………………………………………12

Figure V: Comparison of firing patterns…………………………………………. .……13

Figure VI: Gantt chart of project timeline……………………………………………….16

 

LIST OF TABLES

Table I: Approximate cost of the product………………………………………………..15

Table II: Timeline of the product design…………………………………………………16

 

  1. EXECUTIVE SUMMARY

There has been a considerable measure of advances in medicinal science and building, the world is developing at a very fast pace, where everyone is striving for progress and extravagance. But there are a few people, who have not been honoured with the essential detects (Vision, hear and vocal) by the Almighty; who must be empowered to carry on with their life without difficulties. There are several gadgets that have been planned and manufactured to consider the requirements of such individuals. Numerous people around us have visual difficulties eventually in their life spans. A few cannot see objects which are far off a long way from them, and others can’t read text written in the book. However, these issues can be relieved by eyeglasses, contact focal points or by laser treatment. But, if any section of the visual framework gets harmed, then serious loss of vision may occur. There are about 20-25 million individuals over the globe experiencing such illness. Full loss of vision impacts the life of a person, as it makes them totally dependent on somebody for nearly everything. Re-establishing vision for a person experiencing visual deficiency will be like a miracle for the people suffering from this illness; it is much the same as giving them another life where they can peruse, compose, run, drive and do all that a normal person can. Therefore, a device will be designed which can adequately help re-establish the vision of visually impaired individuals by using the fundamentals of retinal prosthetics.

We tried endeavours, using our designing learning to assist the general population with retinal degenerative illnesses – the general population who is unable to see. In such cases, treatment by prior referred techniques are not enough to fix the issue. We intend to utilize our building information to structure an answer which can fill in as a guide to the general population who are experiencing retinal degenerative diseases.

After an extraordinary consideration, we have arrived at the solution that prosthetic eyes are the best arrangement contrasted with others. It impersonates the working of a real eye. The encoder takes in the picture and changes over it into retina code then the transducer sends it to the cerebrum to create an ordinary retina yield.

On the off chance that we structure a gadget that can imitate the working of the photoreceptors and the front end of the eye, we can get the information signals wanted for the retinal ganglion cells, which would then be able to send electrical heartbeats to the cerebrum, empowering the individual to see. This can happen in light of the fact that the retinal ganglion cells are as yet enduring. Retinal prosthetics falsely invigorate these tissues and empower the individual to see. Retinal prosthetics artificially stimulate these tissues by standard prosthetic eye by encoder and transducer.

While checking on the writing and different assets, we discovered how designing ideas are pleasantly coordinated with organic phenomenon to impersonate the extreme elements of the human cerebrum to accomplish progressive eternal improvement in visual impedance. The device will use an electronic component to capture the image and convert it into a signal that the brain can understand, subsequently bypassing the capacity of damaged part of an eye and empowering the individual to see.

As this product is based on research, the overall time approximation to build this product will be around 1 month 3 days (Gathering electronic components, building eye glass of specific dimensions, Assembling of components and Surgery).

  1. INTRODUCTION

 

Biologists and engineers have been working continuously to find out ways to help the people suffering from such difficulties. If we have a look at the current scenario, there are two types of treatments which can be opted by people suffering from blindness, namely ‘drug therapy’ and ‘prosthetic devices’.

1. Drug therapy involves taking specific form of medication to cure the disease; however, it is rarely helpful for people. A drug named ‘Luxturna’ has been recently approved by the United States Food and Drug Administration (FDA) to treat the retinal disorder, but it’s priced at around $850,000, which is not affordable for common people. [1]

2. Prosthetic devices offer hope for patients with retinal degenerative diseases, such as macular degeneration and retinitis pigmentosa, which affect millions of people worldwide. These diseases cause a progressive loss of the retina’s input cells and the photoreceptors, which leads to severe visual impairment [2]. Most of the patients rely on prosthetic devices, which directly give stimulation to the surviving cells, bypassing the damaged retinal tissues. These devices have been successful to an extent that they enable the patient to see bright/high contrast areas, which assist them a bit while they are moving from one place to another. However, these devices have not been able to give the desired vision to the patients; hence something more needs to be done to improve the result.

 

  1. BACKGROUND & LITERATURE REVIEW

 

3.1 Background review:

It is a common fact that many people in all around the world are facing visual difficulties. In this, some of the difficulty can be mitigated by eyeglass, contact lens or through treatment procedure According to studies, there are more than 20 million visually impaired people all-around the world who needs to be cured. If more than one part of the eye got damaged, total loss of the vision may occur and cannot be cured by treatment. It is a common fact that these people are facing many challenges. With this scenario we have went through different reference papers and we found out different possible solutions and they are smart stick, smart wheel, drug treatment and prosthetic eyes. In these possible solutions, prosthetic eye is the best solution, and this can be done by integrating the engineering concepts and the physiological phenomenon of human brain.

 

The use of prosthetic eye was popular from ancient time onwards. The earliest known prosthetic eye was found in Shahr-I Sokhta, Iran which was made in 2900-2800 BC [3]. Apart from that, evidence from the fifth century BC shows that the earliest prosthetic eyes which being worn outside the socket comes from Egyptian and Roman priests. These evidences clearly describe the use of prosthetic eye from the ancient times. Design of prosthetic eye in the 16th century was worn inside the socket which was made from gold or silver, with coloured enamel coatings [4]. According to researchers, in 17th century more and more people came to this field like glass blowers who were making more realistic prosthetic eyes from glass. In 20th century, new discoveries were arisen in the field of prosthetic eyes and new materials were started to use to produce prosthetic eyes. In this 21st century also new researches for better implant material and design continues. This is the main reason we take prosthetic eye as our solution because there is space for us to incorporate the engineering technical skills.

Figure VII: Late 20th century custom made Poly methyl methacrylate (PMMA) eye [3]

3.2 Literature review:

From ancient history onwards, human eye has been mentioned as the most precious gift. Therefore, the loss of an eye has always been a big misfortune and the person can be only return to their normal life by replacement procedure. So, using prosthetic materials a stimulation of human anatomy can be done to create a perfectly normal eye with surrounding tissue and this procedure is called ocular prosthesis [3]. Most of the patients rely on prosthetic devices, which directly give stimulation to the surviving cells, bypassing the damaged retinal tissues [5].

A prosthetic device or Prosthetic eyeis going to be designed to replace damaged parts of visual system by an electronic device which functions exactly same as an eye. Such devices use electronic component to capture the image and convert it into the signals that brain understands, and this is how prosthetic device bypasses the damaged part and able the person envisioned to the beautiful world [6].

Brain-computer interface are the systems used to control a device with help of the interface connection between brain and computer. This system consists of electronic parts in-order to acquire signals from brain, algorithms generator to decode signals, and some effectors that help user to control. At the point when the client can see the effectors under control, the system is closed-loop so that the client can learn dependent on inconsistencies among planned and genuine kinematic results [7].

H. Keffer Hartline recorded the responses of the retinal ganglion cells and found out that some cells responses to increments of light named as ON cells, some would respond to decrement of light named as OFF cells and some would respond to both named as ON-OFF cells [8].

  1. REQUIRMENT AND CRITERIA

 

  1. Vision Improvement

Improvement in vision of the blind people will be the most important criteria for evaluating the solution. Many devices are available to assist the people suffering from blindness, but they do not offer any improvement in their vision. Although standard prosthetics devices enable the people to see some bright spots of light, but we are willing to go one step ahead of it. We wish to design a device which can significantly improve the vision of the blind.

  1. Safety

The device must be safe for human use. We need to ensure the mechanical stability of the electrodes which will be surgically placed in between the nerve nodes. The materials used to fabricate the device have to be medically tested for safety. To ensure that the device is safe, it will be firstly tested on a population of mice [9].

  1. Reliability and maintenance

If the surgical implantation of the prosthetic eye is done successfully, it is expected to be working for lifetime.

  1. Cost

Average estimated cost for developing a prosthetic eye is $150,000 with an additional charge for surgical implantation and training [10].

  1. Stakeholders/support groups

 

For developing a prosthetic eye, we need support from people belonging to different disciplines including surgeons, biomedical engineers, electronics engineers and the government support.

 

  1. Impact on economy

An estimate suggests that about 20-25 million people worldwide are suffering from retinitis pigmentosa and retinal degenerative diseases, who can be treated with a prosthetic eye [6]. If this is done, we will have 20-25 million people contributing more to the economy and enable the world to utilise the resources in a more efficient and productive manner.

  1. PROPOSED DESIGN/SOLUTION

 

5.1  Working of a normal eye:

Figure VIII: Working of an eye

Firstly, the image from the outside world falls on the cornea of the eye, which focuses the image in a way that it falls sharply on the retina. The photoreceptors work on the image and give signal to the retinal circuitry, which is the middle part of the eye. Now, the information will be extracted from the image and converted into a code, in the form of electronic pulses. These signals are taken by the retinal ganglion cells, also called the output cells and sent to the brain via the optic nerves. These pulses are a combination of patterns which are recognised by the brain. In the real world, the images seen by the eye are changing every second, hence it is very dynamic. Since, the brain receives information in the form of different patterns, it can easily differentiate and recognise them to see different objects clearly [6].

Figure IX: Retinal degenerative diseases [9]

 AMD – Aged macular degeneration
RP – Retinitis pigmentosa

5.2 Retinal degenerative disease – Aged Macular degeneration:

Macular degeneration is a condition in which the photoreceptors in a person’s eye die. With time, the cells and middle circuitry part also dies. Therefore, the part of the eye responsible for converting the images falling on the retina to electric pulses stops working. Although the output cells are completely fine, but due to the degeneration, they do not get any input from the retina and hence they are unable to send any signals to the brain [6].

 

5.3 Retinitis pigmentosa:

It is a hereditary disease in which the person’s eyesight starts failing. Within 5 years, the person turns out to be legally blind, within 10 years the person has no useful vision and within 20 years, their spouce’s eyesight starts failing and they are also trapped in the same vicious circle of this disease [9].

5.4 Symptoms:

Initially, aged macular degeneration does not usually have symptoms. It is generally noticed when it affects both eyes, leading to a blurry spot in the middle of the vision. With time, some of the symptoms which a patient may feel are [11] :

  • Blurry areas in the centre of vision and darkness
  • Poor vision leading to difficulty in reading and driving
  • Difficulty in recognising colors

5.5 Causes:

The primary causes for the disease are age and the genes (hereditary). Other secondary causes are smoking, unhealthy lifestyle, high blood pressure and a poor diet.

Age – The disease is common in old age people. It is more common in women than in men because women tend to live longer than men.

Genes – The disease is hereditary and is passed on from one generation to the next one.

Smoking – Smoking is held responsible for a reducing the oxygen supply to different parts of body including the eyes, hence increasing the chances of getting AMD.

High blood pressure – It is also responsible for reducing the amount of oxygen supplied to various body parts.

Long term exposure to sun – It is believed that sun’s UV rays can damages your eyes if exposed to them for a long period of time and hence may be a reason that person suffers from AMD. [11]

5.6 Design of prosthetic eye

If we design a device that can replicate the functioning of the photoreceptors and the front end of the eye, we can obtain the input signals desired for the retinal ganglion cells, which can then send electrical pulses to the brain, enabling the person to see. This can happen because the retinal ganglion cells are still surviving. Retinal prosthetics artificially stimulate these tissues and enable the person to see [6].

We have two possible solutions to artificially stimulate these tissues, namely:

1.Standard prosthetic eye – A standard prosthetic eye is made up of light detectors enabling the person to see bright spots of light and high contrast edges. But that does not offer too much hope for the patients as they are still not able to perform their day to day tasks properly [6].

2. Prosthetic eye with encoder and transducer – A prosthetic eye with an encoder and transducer has shown much better results than a standard prosthetic eye. Encoder helps in replacing the retinal circuit with a chip. This chip contains mathematical formula coded on it. It works in such a way that image comes in and the chip covert the signal into electrical signal with the algorithms loaded on it. The firing patterns of this device are identical to the normal eyes [6].

Figure X: Schematic of modern prosthetic eye [6]

 

5.7 Components of a prosthetic eye

1. Camera – The camera is used to capture the dynamically changing images from the outside world and serves as an input for the encoder.

2. Encoder – The encoder is based on OMAP 3530 processor designed by Texas instruments. Its primary function is to convert the image into a code which is sent by the optic nerve to the brain and recognised by the brain [6].

3. Transducer – The main purpose of a transducer is that it converts one form of energy or signals into another. It will act as a stimulator, a modified Mini-DLP (Mini digital light projector) [6].

5.8 Working of Prosthetic eye:

The prosthetic eye will constitute a camera, an encoder and a transducer. The camera will capture images of the outside world, which will be converted into a code by the encoder. The encoder will be based on an OMAP 3530 processor. The code developed is in the form of electrical pulses, analogous to the patterns produces by normal retina for the same visual input. This code will be an input signal for the retinal ganglion cells which will be driven by the transducer to fire patterns as directed by the code. The transducers to be used can be either platinum electrodes or optogenetic stimulators like ChR2 [6] [2].

 

5.9 Results and the comparison of the firing patterns:

Figure XI: Comparison of firing patterns from ganglion cells of a normal retina, blind retina treated with a prosthetic eye and a blind retina [2]

A movie of natural scenes was presented to a normal retina, a blind retina treated with encoder-ChR2 method and a blind retina; the firing patterns from ganglion cells were recorded and compared. From the figure, it is very clear that the firing patterns from a blind retina treated with prosthetic eye, is very much similar to the firing patterns of a normal retina. Hence the person treated with this device will be able to see things as a normal person [6] [2].

5.10 Strength and limitations of the design:

Strength – The strength of the design is that it helps to improve the vision of the people suffering from retinal degenerative diseases. It gives a new life to the visually impaired people and makes them independent. The device will serve as curve for never ending hereditary disease. The product will be affordable for the customer as the cost of components for fabrication is reasonable. Although, the product design involves high research and development cost, but it will affordable for the customer. In addition to that the electric power required for operating the device is very low, making it energy efficient. Along with that it takes in the input then process and delivers the output very fast.

Limitations – There may be some surgical complexities and difficulties while implanting the prosthetic eye in the patient. After the successful surgery, if any accident leads to a damage in the components of the prosthetic eye, the rectification process will be very complex and meticulous.

 

  1. COST

 

NO.

COMPONENTS

PRICE IN USD

1

Encoder: OMAP 3530 by Texas Instruments

$80

2

Mini DLP (Digital Light Projector) – Pico projector by Texas Instruments

$499

3

Xlamp XP-E blue LED by CREE Inc.

$14.19

4

Transducer (Channelrhodopsin-2) 

$229.35

4

Surgery expense

$8300

5

Development cost (Research) (Note: This cost does not include in product cost)

$125,000

6

Eye glass

$100

7

Total with Installation

$9222.54

Table I: Approximate cost of the product [2]

  1. TIMELINE

 

Above mentioned product is based on research and is not available in market. Researchers are experimenting such concept on mice as their vision system is similar to those of humans’. Hence, estimating timeline to build such product is not a wise idea. However, approximation-based timeline is mentioned below:

Task

Starting Date

Days

Gathering electronic component

06-11-18

7

Building eye glass of specific dimensions

13-11-18

7

Assembling of components

20-11-18

5

Surgery

25-11-18

15

Completion

10-12-18

Table II: Timeline of the product design

Figure XII: Gantt chart of project timeline

  1. CONCLUSION

 

For living a happy life, blindness or vision impairment is the bottleneck of the person experiencing such disabilities. We have shown multiple solutions of the retinal diseases which causes such vision impairments and came up with a solution of modern prosthetic eye which will bring unbelievable change in the world.

Drug therapies, laser treatments, contact lenses, eye glasses are good enough to treat partially visually impaired eyes. However, there is no treatment defined for fully visually impaired eyes yet, except the solution we proposed in this report which is called a Prosthetic eye or Bionic eye.

Implementing engineering fundamentals to biological concepts, researchers have created such modern technological advancement in very new emerging field of study known as ‘Biomedical Science.’

The approximate cost of prosthetic eye is nearly $9500 which is easily affordable to a common man or with health support services of respective governments. We believe, this is the most perfect option we may have which can improve someone’s visual system as no other device can improve fully blinded eyes. We always keep looking for any advancement possible in existing patent of the device.

Recommendations:

Researchers have done tremendous work to build an advanced prosthetic eye by working on biological neural network and modern electronics concepts. Technological advancement is subject to progressive modifications with respect to time and therefore, we would recommend little modification to make the device more advanced. The product contains an eye glass with camera enabled and attached with transducer and encoder which are Surface Mounted Devices (SMDs).

In past one-decade, fine research work has been done in neural circuits. Neural circuits are those electronic devices which are capable of processing data without any commands and capable to make decision by themselves. Therefore, introducing semiconductor neural memory, this device can store the pictures that patient has seen and can be recalled even after storing them temporarily.

  1. REFERENCES

 

[1]

U.S. Department of Health and Human Services, “LUXTURNA,” U.S. Food and Drug Administration, 26 July 2018. [Online]. Available: https://www.fda.gov. [Accessed 1 10 2018].

[2]

S. N. a. C. Pandarinath, “Retinal prosthetic strategy with the capacity to restore normal vision,” in Proceedings of the National Academy of Sciences of the United States of America, 2011.

[3]

A. Sajjad, “Cureus,” 06 December 2012. [Online]. Available: https://www.cureus.com/articles. [Accessed 2 10 2018].

[4]

D. K. FARROKH, “The official web site of DR. KAVEH FARROKH,” [Online]. Available: https://kavehfarrokh.com/iranica/maps-of-iran-5000-bc-651-ad/the-worlds-oldest-known-artificial-eye/. [Accessed 3 10 2018].

[5]

B. S. -. President, “Using AI to empower people with disabilities,” Microsoft, 07 May 2018. [Online]. Available: https://blogs.microsoft.com/on-the-issues/2018/05/07/using-ai-to-empower-people-with-disabilities/. [Accessed 01 10 2018].

[6]

S. N. a. C. Pandarinath, “Retinal prosthetic strategy with the capacity to restore normal vision,” Journal of US National Institute of Health, vol. 109, no. 37, pp. 15012-15017, Aug 2012.

[7]

D. M. P. J. P. C. L. P. Josh Merel, “Encoder-Decoder Optimization for Brain-Computer Interfaces,” PLOS, 01 June 2015. [Online]. Available: https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1004288. [Accessed 02 10 2018].

[8]

Y. R. S. N. Illya Bomash, “A Virtual Retina for Studying Population Coding,” PLOS, 14 January 2013. [Online]. Available: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0053363. [Accessed 02 10 2018].

[9]

P. R. Shepherd, Writer, The Bionic Eye prototype: Professor Rob Shepherd at TEDxU Wollongong. [Performance]. TEDx, June 2012.

[10]

B. Yard, “Blind man wants provincial government to pay for his chance to regain sight,” CBC , 06 June 2017. [Online]. Available: https://www.cbc.ca/news/canada/new-brunswick/bionic-eye-blind-arseneau-prosthesis-government-nb-sight-1.4146648. [Accessed 01 10 2018].

[11]

National Eye Institute, American Academy of Ophthalmology, “Age-Related Macular Degeneration Overview,” WebMD, LLC, [Online]. Available: https://www.webmd.com/eye-health/macular-degeneration/age-related-macular-degeneration-overview#1. [Accessed 04 10 2018].

[12]

D. K. Farrokh, “The World’s Oldest known Artificial Eye,” [Online]. Available: http://kavehfarrokh.com. [Accessed 04 Nov 2018].

[13]

B. S. F. R. J. P. Keith Pine PhD, “A BRIEF HISTORY OF PROSTHETIC EYES,” University of Auckland, Auckland.

 

 

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